Twenty-five children, from an original number of 52, will continue to be followed to their 5-year longitudinal termination in this ongoing study of the relationship between sebaceous gland development, acne, androgens, and pubertal development. In each subject, forehead sebum samples will be collected 4 times yearly and the relative composition of lipids analyzed by thin-layer chromatography. Physical examinations will be done twice yearly and include height, weight, and other signs of pubertal maturation. In 15 subjects, 24-hour urine specimens will be collected twice yearly and analyzed for testosterone, total 17-ketosteroids and creatinine. In subjects, 3-hour sebum production tests will continue to be performed. In addition to providing possible markers of early pubertal maturation, normal and abnormal, by skin measurements, the results of these studies may serve to identify, at an early age, children at risk for the development of significant acne and thereby consideration afforded for earlier therapeutic intervention.